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Sorbus wilmottiana 

Scope: Global
Language: English
Status_ne_offStatus_dd_offStatus_lc_offStatus_nt_offStatus_vu_offStatus_en_onStatus_cr_offStatus_ew_offStatus_ex_off

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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Rosales Rosaceae

Scientific Name: Sorbus wilmottiana E.F.Warb.
Common Name(s):
English Wilmott's Whitebeam
Taxonomic Source(s): The Plant List. 2017. The Plant List. Version 1.1. Available at: http://www.theplantlist.org/.

Assessment Information [top]

Red List Category & Criteria: Endangered D ver 3.1
Year Published: 2017
Date Assessed: 2016-05-24
Assessor(s): Beech, E., Rich, T.C.G. & Rivers, M.C.
Reviewer(s): Salvesen, P.H. & Allen, D.J.
Justification:
Sorbus wilmottiana is a shrub or small tree with a restricted to the Avon Gorge in England. It is assessed as Endangered (EN D) as there are thought to be only about 60 mature individuals. It is severely range restricted with an extent of occurrence and an area of occupancy of less than 8 kmĀ². It has a poor conservation record with several trees being removed as part of conservation work, and is now at risk from a fungal disease.

Geographic Range [top]

Range Description:This species is endemic to western England, where it is known from both sides of the Avon Gorge in Somerset and Gloucestershire (Rich and Houston 2004). The area of occupancy (AOO) will be less than 0.5 km2, however measured with the recommended 2x2 km grid the AOO is 8 km2. The estimated extent of occurrence (EOO) of 0.5 km2 is increased to 8 km2 to equal AOO.
Countries occurrence:
Native:
United Kingdom (Great Britain)
Additional data:
Estimated area of occupancy (AOO) - km2:8Continuing decline in area of occupancy (AOO):No
Estimated extent of occurrence (EOO) - km2:8
Continuing decline in extent of occurrence (EOO):No
Lower elevation limit (metres):5
Upper elevation limit (metres):110
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is known from the Avon Gorge with 97 individuals in 2016 (L. Houston and T. Rich pers. comm. 2016); it is thought that about 60 of these are mature individuals. There are many young plants in the population and the population is thought to be stable. In the 1990s some individuals were cut down during conservation or amenity work, two of which have not recovered (Rich et al. 2010).
Current Population Trend:Stable
Additional data:
Number of mature individuals:60Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No
All individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:Sorbus wilmottiana is a shrub or small tree that can grow at least 10 m tall. It is found on rocks and quarry faces in open rocky woodland and scrub as well as in open grassland and woodland clearings. Its seeds are dispersed by small mammals and birds. It is thought to be light demanding like many other Sorbus species as it is rarely found in closed woodland. Saplings found during surveys suggest that the population is regenerating (Rich et al. 2010).
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:No

Use and Trade [top]

Use and Trade: The species is not utilised.

Threats [top]

Major Threat(s): In the 1990s eight or nine plants were cut down during conservation or amenity work, two of which have not recovered (Rich et al. 2010). Currently it is under threat from a fungus disease affecting a few plants. The upgrading of a railway line on the western side of the gorge may affect some plants.

Conservation Actions [top]

Conservation Actions: All known trees are currently within the Avon Gorge SSSI (Site of Special Scientific Interest) and SAC (Special Area of Conservation) (Rich and Houston 2004). It is listed as a UK BAP priority vascular plant species (JNCC 2010).

Sorbus wilmottiana is reported as held in 13 ex situ collections (BGCI 2015) and is recorded as present in an ex situ seed bank collection (ENSCO 2015).

The species was assessed as Critically Endangered (Oldfield et al. 1998; Cheffings and Farrell 2005) but after further individuals were found in 2009, considered Endangered in Rich et al. (2010) and (Stroh et al. 2014). Further research is needed into the fungal disease.

Citation: Beech, E., Rich, T.C.G. & Rivers, M.C. 2017. Sorbus wilmottiana. The IUCN Red List of Threatened Species 2017: e.T34732A80736838. . Downloaded on 21 November 2017.
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